It's not only the lack of a single heir to President Bush that makes the race so open; it's that the more one examines the front-runners for each party, the more flaws one finds. Depending on the week, I change my mind about who is the weaker front-runner, New York Sen. Hillary Rodham Clinton (D) or Arizona Sen. John McCain (R).

Neither has a stranglehold on the respective party's nomination. For now, McCain seems slightly stronger than Clinton simply because he can at least point to electability in the general as an asset. Clinton cannot do that... yet.

This is going to be the busiest off-year in presidential campaign history. There will be more "decisive" moments this year than in any previous off-year. From debates this spring and summer to straw polls this fall that actually cause candidates to drop out, 2007 will arguably be busier for presidential campaign reporters than 2008. After all, we should know who the two major-party nominees are by Feb. 5, 2008, allowing for the longest general election campaign ever.

Of course, handicapping candidates may be pointless if Iraq remains the voters' top concern in 2008. Maybe '08 will be like '68 and the war will make the race unwinnable for the party in power no matter whom the opposition nominates. I mean, the Republicans won in '68 with Richard Nixon... Richard Nixon! So anything is possible, especially when the country is in the midst of an unpopular war.

Given that we've already gained a front-runner (Sen. Barack Obama, D-Ill.) and lost one (ousted Sen. George Allen, R-Va.), predicting anything beyond the next week is not prudent. Given that disclaimer, we (meaning The Hotline's associate editor, Marc Ambinder, and I) debut our White House rankings for 2007. Remember, these candidates are ranked in order of how things stand now, not how we think things will stand in a few months.

We'll be updating these rankings weekly in 2007 since, as we're arguing, the race will be incredibly busy for the next year. Also, everyone will be ranked now, not just the top five.

The Republicans
1. John McCain (last ranking: 1)
Just look at the list of "Straight Talk" and "Explore McCain" supporters that the Arizona senator has signed up and it's hard not to call him the front-runner. Considering that McCain made the decision to start his presidential committee in 2006 rather than waiting until 2007 tells us he could have a surprisingly big fundraising total right out of the starting gate this year. Maybe it's a way to send a message to the GOP establishment that the train is leaving the station.

The expectations bar is playing out just right for McCain. Those in the know know he's the front-runner, but the polls continue to show former New York City Mayor Rudy Giuliani on top in primary matchups, keeping expectations for McCain in check. And the harder Giuliani takes a look at this race, the better for McCain, because the longer this is a three-or-more-way race, the easier it is for him to win Iowa. And the winner in Iowa will probably end up being the nominee.

By the way, McCain's Iraq position may be brave, but it's unpopular right now. While that might be "straight talk," it may not be politically viable come 2008. Iraq could ultimately be the biggest hurdle for the 70-year-old.

2. Mitt Romney & Rudy Giuliani (last rankings: 2 & 3)It's a tie between outgoing Massachusetts Gov. Mitt Romney and Giuliani. After a rough December that saw increased scrutiny into Romney's record, we've slid him down just a bit into a tie for second. Romney has done an excellent job in lining up key talent and has certainly shown that he belongs in the top tier. But will conservatives who are desperate for a McCain alternative turn up their noses at Romney? It's possible. There are some Romney fans (i.e. folks who are supportive but aren't paid advisers) who are concerned that he portrayed himself as too conservative in the last few months, which opened him up to the "flip-flopping" criticism he's received over the last few weeks.

As for Giuliani, "America's Mayor" is clearly more serious about running than we've believed. The hiring of Republican National Committee ace Mike DuHaime sent that message to official Washington loud and clear. But take a look at the coverage Giuliani's "stolen" campaign plan received from the New York City press corps. That's the type of scrutiny Giuliani has to be prepared for, and that McCain will never receive. Whether that's fair is not for us to decide, but it's simply the reality a Giuliani campaign will face. He's holding up strong in the polls, however, so it's hard to discount him. Plenty of his rivals love to whisper that Giuliani doesn't truly have the ambition to stick it out for a campaign that will be more grinding than anything he's ever experienced. We'll see; he's already been in this race a lot longer than we thought.

4. Newt Gingrich (last ranking: unranked)Looking for a dark horse to bet on in the Iowa caucuses? Then look no further than former House Speaker Newt Gingrich of Georgia. The conservative vacuum among the top three front-runners means someone is going to emerge, right? At least, that's what guys like Gingrich (and the umpteen former governors who are suddenly running) keep telling themselves. But there's a very credible case for Gingrich should he stay with his timetable of announcing very late (as far as this calendar is concerned), around Labor Day '07. He'll be new and old at the same time; he'll dominate the media like no one else can (he's a great interview), and he'll be surprisingly engaging on the trail. But he's got higher negatives than anyone on the GOP side, and that is what keeps him out of our top tier for now.

5. Sam Brownback (last ranking: unranked)Thanks in part to the lack of attention on outgoing Arkansas Gov. Mike Huckabee, Kansas Sen. Sam Brownback's bandwagon appears to be one worth jumping on for social conservatives. His schtick is tailor-made for the Iowa caucuses, and while it's hard to imagine a scenario that puts Brownback on top in Iowa or New Hampshire, it's fairly easy to see how he could become the surprising second- or third-place finisher in one of the two early states, guaranteeing him some role in the determination of who gets the nomination. Look for Brownback to be treated very kindly by all three GOP front-runners, because McCain, Romney and Giuliani will not want to alienate someone who could become a kingmaker.

6. Mike Huckabee (last ranking: 4)For someone with such potential, he's taking his sweet time putting together a team. The money question was always huge for the other man from Hope, and his late start in comparison to his potential second-tier rivals is troublesome. Still, he's a potential media darling, which is why we've ranked him high in previous lists.

7. Chuck Hagel (last ranking: unranked)A while ago, a Republican F.O.H. ("friend of Hotline") remarked to us that there would be no room in the GOP primary for an anti-war candidate. While that may be true, we'd argue that there might be room for a credible anti-Iraq candidate, and Nebraska Sen. Chuck Hagel would be a credible messenger on the issue. It certainly would allow him to separate himself from the guy he's always compared to: McCain.

8. Jim Gilmore, Frank Keating & Tommy Thompson (last ranking: unranked)A three-way tie between former governors -- Virginia's Jim Gilmore, Oklahoma's Frank Keating and Wisconsin's Tommy Thompson. For now, the nascent candidacies of this trio are being lumped together because they are all due to the conservative vacuum. All claim to be pragmatic conservatives, and there could be room for one of them to break through. Keating's always struck us as someone who should be on a bigger stage, and perhaps he could become the Howard Dean of this GOP field (i.e., the small-state former governor who catches fire). As for Gilmore, too many Virginians are still paying a car tax for his candidacy to get decent hometown support. And Thompson is probably eight years too late, something that no doubt frustrates the one-time king of Wisconsin.

The Democrats
1. Hillary Rodham Clinton (last ranking: 1)
The best thing to happen to Clinton may be the rise of Obama, because for the time being, the glare is off of her while she readies herself for a run. Sure, she'll get incredible scrutiny, but it will be nowhere near the scrutiny she'd be getting if Obama wasn't sharing the "gee whiz" stage right now. Still, the Obama buzz ought to scare her for this reason: There's clearly a hunger (be it in the media, the Democratic establishment or even among actual voters) for an alternative to Clinton. These Democrats probably won't dump her for just any Christopher Dodd, Bill Richardson or John Edwards that comes along, but for a guy like Obama, it's tempting.

Clinton can't just keep grinding this out. The earlier she gets in, the better. As John Kerry (D) proved in '03-'04, it's better to get your bad months out of the way early and then be a comeback candidate later in the year. She can survive a long campaign better than most front-runners and ought to see that as an advantage. Don't be surprised if she fires things up a bit sooner than Bush's '99 playbook (which Clinton folks seem to like) calls for.

2. Barack Obama (last ranking: 3)The one question most smart Democratic operatives have right now: Can he keep this pace up? As one F.O.H. who loves track puts it, Obama is running a marathon at a sprinter's pace. As for whether Obama is running, it's hard to imagine that he won't at this point. He's doing too many of the little things now that indicate he's running (including sending "thank-you" postcards to New Hampshire Democrats late last month). In fact, if Obama backed out now, he'd probably lose enough credibility that his stock would never be the same. Think former New York Gov. Mario Cuomo (D) in '92. So, count Obama as a candidate.

(Actually, the person this may help the most is McCain. If the media stays as ridiculously fascinated with the Clinton v. Obama storyline as they have been the last month, there may not be enough media energy to cover a fight on the right.)

3. John Edwards (last ranking: 2)No one has been hurt more by Obama than Edwards. He was in a great position before the Obama boomlet, but now he's that one-time fresh face of '04 who's running again. All of Edwards' strengths may fade away with Obama in the race, because the vacuum that will be left in the Democratic primary won't be for a liberal like Edwards, and instead will be for a senior statesman (like Dodd or Joseph Biden). Still, Edwards is enormously popular in Iowa thanks to the fact that the last time anyone has ever run a negative TV ad against him was in the '98 North Carolina Senate race. If Edwards' Iowa support is more than an inch deep, then he'll be around a while. But if not, this run could mirror Tennessee Sen. Lamar Alexander's short-lived '99-'00 campaign.

4. Tom Vilsack (last ranking: unranked)Outgoing Iowa Gov. Tom Vilsack has climbed his way up to the top five thanks to an impressive announcement and attrition (the departures of former Virginia Gov. Mark Warner and Indiana Sen. Evan Bayh). Vilsack is set up as the token centrist of the field, and while conventional political wisdom says that won't work in a Democratic primary in '07-'08, he shouldn't be counted out. The big question for Vilsack: how does he "win" Iowa? Because even a "win" may not be a "win." Discuss...

5. Bill Richardson (last ranking: unranked)Among some Democratic strategists who are not yet committed to a candidate, there's chatter that the next candidate to follow Warner's and Bayh's stares into the '08 abyss and pull the ripcord is New Mexico Gov. Bill Richardson. At the end of the day, these folks claim, he's a pragmatist. His resume is gold, but the novelty factor (he'd be the first Hispanic) is getting eclipsed by Clinton and Obama. He does seem intent on giving this a try. Let's see what the money reports show in the spring.

6. Joseph Biden, Christopher Dodd & Wesley Clark (last ranking: unranked)A three-way tie between senior statesmen Biden, Dodd and retired Gen. Wesley Clark. One interesting thing about Obama's candidacy is that it opens up a vacuum in the primary. Follow this train of thought: Obama's inexperience highlights Clinton's relative inexperience, which highlights Edwards' inexperience, which leaves room for someone to play the "let's not go the Bush route again" card. And while Delaware's Biden, Connecticut's Dodd and Arkansas' Clark all have their flaws, all can claim uber-experience to actually do the president's job, and it's possible the Iowa caucus-goers may demand an experienced candidate in the mix.

9. John Kerry (last ranking: 5)It may seem mean that we've dropped the '04 nominee this far down our list. But he seems less sure about a run, which is why we've dropped him. If he indicates that he's leaning more toward running, then we'll move him back up.

The Wild Cards
These are candidates who aren't running now but could at a later date:

1. New York City Mayor Michael Bloomberg: He seems more intrigued by the indie idea than ever before.

2. Former Vice President Al Gore: He stubbornly refuses to say 'never.'